PM/AM: These Microbes Shoot Alien-Like Tentacles to Breathe

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Shewanella bacteria are already kind of weird—they breathe solid iron and can thrive in both oxygen and oxygen-free environments. But things just got weirder. A team of researchers has filmed a video of these microbes shooting out strange tendrils from their cells. And it definitely feels like it's out of a sci-fi movie:

So what are these wires? Scientists had previously thought they were pili, or the little hair-like structures that protrude from bacteria, because they looked so similar. But research published yesterday in the Proceedings of the National Academy of Sciences suggests a different mechanism: the strings are related to proteins on the microbe's outer membrane which are involved in transferring electrons for energy.

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In aerobic environments, these microbes donate electrons to oxygen for energy, much like we do. But when there's no oxygen around, the bacteria have to branch out to other materials. They shoot out these little cables and shuttle electrons to iron oxides and other solids as a way to power up the microbial cells. When the researchers looked at the genes expressed in anaerobic conditions, they found more electron transfer genes, rather than pili genes for pili. Then the scientists designed an experiment that could capture the morphing process in real time, and saw that the tendrils came from the outer membrane, not the pili.

It sounds like there's some potential to develop a bio fuel cell with these little guys. And of course, knowing how these bacteria survive in harsh environments can give us clues to what we might encounter on different planets, moons, and comets. Either way, it just goes to show that Shewanella is one crazy microbe.

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